Magical Thinking Fails

The more a country depends on such sources of energy, the more there will arise – as Germany is discovering – two massive technical problems. One is that it becomes incredibly difficult to maintain a consistent supply of power to the grid, when that wildly fluctuating renewable output has to be balanced by input from conventional power stations. The other is that, to keep that back-up constantly available can require fossil-fuel power plants to run much of the time very inefficiently and expensively (incidentally chucking out so much more “carbon” than normal that it negates any supposed CO2 savings from the wind).

4 Responses to Magical Thinking Fails

There are several aspects of “green” generation I believe have been badly neglected: 1.Solar, and to a lesser extent wind, provide no system inertia, no frequency stability. Solar outright trips upon loss of hz while wind farms have no governor in which to set a droop setting. 2. Alternative power sources provide no voltage support. Generators with automatic voltage regulation provide dynamic response to system disturbances. Solar in particular, because of their conversion from DC power, trip during relatively minor (fault induced) faults. 3. The propagation of small individually owned solar units acts as hidden load waiting to be sprung upon the unsuspecting power dispatcher. In the past, on a summer day,when a cloud comes over the city the dispatcher sees a drop in load. Now the load may even rise. Is there an effective way of accounting for this? How does the operator know if there is enough spinning reserve to cover hidden generation? 4. This last point may make me sound like an ignorant peasant storming the castle holding a torch and pitch fork. I fear that despite the oversight of so many wise engineers, there may be overlooked properties associated with large solar facilities. In the early seventies resonant frequencies were overlooked in the design of the interconnected EHV system. Could there be another “subsynchronous resonance” waiting?
Thanks for listening to my worried rant.

“…to keep that back-up constantly available can require fossil-fuel power plants to run much of the time very inefficiently and expensively”

The idiocy of running fossil fueled plants as “back-up” is where the inefficiency and extra expense come from. These plants have been providing our electricity for generations at rates low enough to power our increasing standards of living. Now that the Sierra Club is in charge, though, we are abandoning what has worked for politically-correct power sources that will be neither reliable nor cheap. The effect of sky-high utility rates on industry and homeowners will be catastrophic. I just hope the public is smart enough to know who to blame.

Not an electrical engineer, but I am familiar with the Inverse Square Law, E = (I cos theta ) / d2. The interesting part of that is the cosine theta part–because it basically means the further angled away from the normal of the sun’s rays, the less light is hitting the surface. So solar panels in Germany get MUCH less light on them than say, a solar panel in the Mojave Desert than, oh, say a solar panel in Quito, Ecuador. Then consider the number of overcast or hazy days, further reducing the amount of the sun’s rays making it through to the solar panel. And Germany has about 200 cloudy days annually, on average. Wishful thinking is right!